Fan for air handling system

Abstract

A fan unit for a building's air handling system comprising a support structure including a front wall with an air inlet opening formed therein and a bladed fan wheel rotatably mounted on the support structure about its central axis and having an axial air intake on a front side thereof confronting the inlet opening. The fan wheel has an annular air outlet extending about its circumference. A fixed centerbody directs air flow into and within the fan wheel and extends along the central axis from a relatively narrow front end located in the air inlet opening to a wider rear end located within the fan wheel. This centerbody has an annular exterior surface which curves outwardly in a section thereof adjacent the wider rear end. The centerbody extends through the axial air intake of the fan wheel. Support struts rigidly support the centerbody in a fixed position. Preferably the centerbody is filled with sound attenuating material. Preferably the fan unit has an additional wall spaced from the front wall and these two walls extend radially away from the annular air outlet forming an annular air passageway that opens into an interior air space. Both the front wall and the additional wall can contain sound attenuating material. The width of the passageway increases as it extends away from the annular air outlet.